Digital pulse width modulators are circuits to produce pulse width modulation (PWM) signals. Digital pulse frequency modulators are circuits to produce pulse frequency modulation (PFM) signals. For PWM signals, the widths of the pulses are varied at constant frequency. For PFM signals, fixed-duration pulses are sent at varying frequencies. Both PWM and PFM signals are used to produce DC power output voltages.
The PWM and PFM signals are used to control external switches to input a power voltage and ground into an external LC circuit comprised of an inductor and an output capacitor. The greater the PWM (or PFM) signal duty cycle (fraction of time high), the greater the DC output voltage.
The PWM (or PFM) signal is typically fed into an external deadtime circuit that produces a high side (HS) PWM (or PFM) signal for a high side switch and a low side (LS) PWM (or PFM) signal for a low side switch. The external deadtime circuit can insert a deadtime where neither the high side nor the low side PWM (or PFM) signal is high to prevent both the high side and the low side switches from being on at the same time.